the command will trap the level 4 till the most severe level ie; warning till emergency.
The syslog levels and descriptions are listed below:
Code Severity Description
0 Emergency system is unusable
1 Alert action must be taken immediately
2 Critical Critical conditions
3 Error Error conditions
4 Warning Warning conditions
5 Notice normal but significant condition. I
6 Informational Informational message
7 Debug Debug-level message